Thermocouples (TCs) have proven invaluable in thermoelectric energy conversion. Their ability to generate electrical power, low cost, and high sensitivity make them ubiquitous in applications ranging from industrial control to home thermostats, including on-chip differential thermometry, energy harvesting, and detection of millimeter waves and infrared radiation. The operating principle of TCs is based on the Seebeck effect, which is the property of an electrical conductor to develop an electric field in response to a temperature difference across it. Different materials will exhibit this property to varying degrees, meaning for a given temperature gradient across two different materials a different voltage potential may be generated.
Thermocouples have been constructed from two dissimilar conductors (A and B) having different absolute Seebeck coefficients (SA and SB). An open-circuit voltage, VOC, develops across the hot and the cold junctions in response to a temperature difference, ΔT. The open-circuit voltage is proportional to both this temperature difference and the difference in absolute Seebeck coefficients according to equation (1).VOC=(SA−SB)ΔT  Eqn (1)
Fabrication of bi-metallic thermocouples is necessarily complicated by the fact that two different metals must be fabricated to form a physical junction there between. This fabrication process is made even more difficult at submicron scale which requires finer control due to the smaller dimensions. Current fabrication methods for bimetallic junctions include lithographic and growth methods. The requisite control methods and fabrication method for bi-metallic thermocouple fabrication can be expensive and cumbersome. Therefore, there exists a need for a thermocouple design which would eliminate these difficulties.